The present invention relates to an assembly comprising an articulation spindle supported by a clevis and immobilized in translation by a blocking device integrating a double anti-rotation system.
In the field of aeronautics, according to one configuration shown in FIG. 1, an engine 10 is connected to a wing 12 of an aircraft via the intermediary of an attachment pylon 14.
The attachment pylon 14 is connected to the wing 12 via the intermediary of fasteners 16, 16′, at the front and at the rear of the attachment pylon. In parallel, the engine 10 is connected to the attachment pylon 14 via the intermediary of fasteners 18, 18′, at the front and at the rear of the engine. The connection between the engine 10 and the attachment pylon 14 comprises lateral link rods 20 which take up the thrust forces generated by the engine 10, each lateral link rod 20 being connected at a first end by a fastener 22 to the engine 10 and at a second end by a fastener 22′ to the attachment pylon 14.
Some of these fasteners 16, 16′, 18, 18′, 22, 22′ comprise at least one assembly with an articulation spindle connecting a clevis and a ferrule.
One embodiment of an assembly provided at the fastener 18′ connecting the engine 10 and the attachment pylon 14 at the rear of the engine is shown in FIG. 2.
This assembly comprises a clevis 24 connected to the attachment pylon 14, a ferrule 26 connected to the engine and an articulation spindle 28 connecting the clevis 24 and the ferrule 26.
The clevis 24 comprises two arms 30, 30′, each comprising an inner face 30I, 30I′ and an outer face 30E, 30E′, wherein the inner faces 30I and 30I′ face each other.
Each arm 30, 30′ comprises a bore 32, 32′ into which is inserted a sleeve 34, 34′, the two sleeves 34, 34′ being coaxial and aligned and having equal internal diameters.
In the following, the longitudinal direction corresponds to the direction of the axes of the sleeves 34, 34′.
Each sleeve 34, 34′ comprises an outer shoulder 36, 36′ which presses against the inner face 30I, 30I′ of the arm into which it is inserted, so as to limit the movement in translation of said sleeves 34, 34′ in the longitudinal direction.
The ferrule 26 comprises a swivel bearing 38 with a bore 40 whose diameter is substantially equal to the internal diameter of the sleeves 34, 34′.
The articulation spindle 28 comprises a hollow cylindrical body whose outer diameter is substantially equal to the internal diameter of the sleeves 34, 34′ and the diameter of the bore 40 of the swivel bearing 38.
In order to avoid the articulation spindle 28 coming out of the sleeves and the fastener coming apart, the assembly comprises a blocking device for immobilizing the articulation spindle in translation in the longitudinal direction.
According to a first embodiment shown in FIG. 2, the blocking device comprises:                a bolt 42 with a shank 44 housed in the articulation spindle 28, a head 46 at a first end of the shank and a threaded portion 48 at a second end of the shank,        a self-locking nut 50 which is screwed onto the threaded portion 48 of the bolt 42,        a first washer 52 which is interposed between the head 46 of the bolt and the articulation spindle 28 and whose outer diameter is greater than the outer diameter of the articulation spindle,        a second washer 54 which is interposed between the nut 50 and the articulation spindle 28 and whose outer diameter is greater than the outer diameter of the articulation spindle,        a pin 56 which passes through the nut 50 and the shank 44 of the bolt so as to immobilize the nut 50 with respect to the bolt 42.        
According to this embodiment, the self-locking nut 50 corresponds to a first anti-rotation system and the pin 56 corresponds to a second anti-rotation system.
During assembly, the bolt 42 is introduced from a first end of the articulation spindle 28 whereas the nut 50 and the pin 56 are maneuvered from a second end of the articulation spindle. As a consequence, this first embodiment requires free space on both sides of the clevis 24.
In order to remedy this drawback, and to allow assembly from just one side of the clevis, a second embodiment shown in FIG. 3 has been developed.
This embodiment is more particularly suited to fasteners 18 located at the front of the engine 10.
Those elements which are in common with the first embodiment are referenced in the same manner.
According to this second embodiment, the sleeve 34 of the first arm 30 of the clevis 24 comprises at a first end an outer shoulder 36 which projects out from the sleeve and which bears against the inner face 30I of the first arm 30 and at a second end an inner shoulder 58 which projects into the sleeve and which acts as a stop against which a first end of the articulation spindle 28 can come to bear in order to limit the movement thereof in translation in the longitudinal direction in a first sense indicated by the arrow 60 in FIG. 3.
The sleeve 34′ of the second arm 30′ of the clevis 24 comprises at a first end an outer shoulder 36 which projects out from the sleeve and which bears against the inner face 30I′ of the second arm 30′ and at a second end an extension 62 which extends beyond the outer face 30E′ of the second arm 30′ and which comprises a tapped bore 64 whose diameter is greater than the internal diameter of the sleeve 34′.
According to this second embodiment, a blocking device makes it possible to limit the movement in translation of the articulation spindle 28 in the longitudinal direction in a second sense indicated by the arrow 66 in FIG. 3. The blocking device comprises:                a first headless screw 68 which is screwed into the tapped bore 64,        at least one elastic washer 70 interposed between the second end of the articulation spindle 28 and the first headless screw 68,        a second headless screw 72 which is screwed into the tapped bore 64 and presses against the other side of the first headless screw 68 from the elastic washer(s) 70,        a flexible or rigid longilinear element 74 which passes through the extension 62 and the second headless screw 72 so as to immobilize said second headless screw 72 in rotation with respect to the extension 62.        
The longilinear element 74 corresponds to a first anti-rotation system and mounting the first headless screw 68 between at least one elastic washer 70 and a second headless screw 72 corresponds to a second anti-rotation system.
This second embodiment has the advantage that it is possible to carry out the assembly from just one side of the clevis.
However, installing the headless screws 68 and 72 inside the tapped bore 64 is not easy and requires the use of tools. This installation is even more difficult when the articulation spindles are of smaller diameter. Indeed, in this case, it is necessary to exert a relatively large torque given the small diameter of the headless screws in order to compress the elastic washer(s) and obtain the second anti-rotation system.
The present invention aims to remedy the drawbacks of the prior art.